Method of facilitating the removal of beads that adhere to ferrous metal cut thermochemically



Feb 13, 1951 w. T. DAVIS 5,

METHOD OF FACILITATING THE REMOVAL OF BEADS THAT ADHERE T0 FERROUS METAL CUT THERMQCHEMICALLY Filed D60. 50, 1947 Patented Feb. 13, 1951 UNITED STATES. PATENT orncei METHOD 'OFFFAOIEITATINGI THE REMOVAL; OF BEADSEZTHAT ADHERE 'LTO FERROUS METALLCIIIL. THERMOCHEMICALLY William'iT. Davis,.pRoseland, N. J assignor to Air ReductiomCompany, Incorporated;..a.-corpora-! tion of New York Application.Decemben130, 1947; Serial 'No'; 794,536

Z CI'aLiI'nS: (CL..1. 48.9)

This invention relates to improvements in the l thermochemical cutting. of ferrous; metal by means of "an oxygen jet and more "particularly. to

This is =particularly true wherrcutting hot metal".

at 'irollin'g' ;or -forgingtemperatures. Sometimes tfieibeadsare difficult to rem'ovezwh'en they form onzwork' that is cold-cut andcan be removed only-by using abrading-oncutting methods such as-zgrinding or chipping themiofiiii but theyare nearly always difficult to remove when they form on work that .has been cut-while hot because they actually become welded'to the hot base metal."

Theiobje'ct of this invention is "to convert the dense adhering beads into porous' lightly adhering beads that can be very easily removed .leaving sharp bead-free corners on the work.

7 This result is achieved by projecting Water against the molten products resulting from the cutting operation and which cling to the work along the bottom edges of the kerf. The water instantly forms steam pockets in the molten material clinging to the work and accelerates its solidification, creating spongy porous masses in place of the usual dense beads. The porous beads do not adhere tenaciously to the base metal but can be easily cracked ofi or readily removed by a slight blow or by reheating as is done in a descaling operation, leaving sharp bead-free edges on the work. A simple tumbling operation is one easy way of removing the beads.

In the preferred form of the method the water is projected in the form of a stream into the kerf closely behind the cutting-oxygen jet and from that side of the work-piece at which the cuttingoxygen jet is directed against it, the stream of water being divergent so that it strikes the side walls of the kerf preferably nearrthe bottom of the kerf and so that it contacts with the molten products clinging to the work along the bottom edges of the kerf.

Apparatus suitable for carrying out the method is illustrated in the accompanying drawings, in which:

Figure 1 is a perspective view of the apparatus and awork-piece being cut by it;

Fig 2 is a-.1 vertical section .of. the worke'piecei takenalong the line of .the cut and-showingth'e' tip-ends ofthe cuttingtorch and thewwater projecting nozzle in side elevation;

Fig. 3 is atransverse "section of the workpiece showing the tip-end of the waterinozzlein front elevation and illustrating .the divergent or expanding nature of the. water stream.

Referring to. the drawings,- the -cutting,.torchl. is shown at -I ii and thewaternozzle atll l .l These. may .beh'eld in properrelationto each other and". moved along a ferrous metal. .work-piece m.

any suitable way. In the.particularapparatus illustrated in thedrawingthey are mounted Tona torch carriage l2 running on ..track rails 13';

Thecarriage is electrically driven at a"constant' speed determined by the setting of "a'governorifll associated with the carriage motor; An'arm' l5' supports atorch holder '56 in which the cutting"; torch'is mounted. The cutting torch'may'bea machine'type torch'of standard designand'need not be described in detail. It "is adapted to pro-= ject heating flames against the Work to raisethe' metal to kindling temperature and w directajet of 'cutting-oxygen against the'workto cutit thermochemically as is Well'understood in the" art. An auxiliary arm l1 extending from the torch arm I5 carries an auxiliary holder l8 in which the water nozzle H is mounted. Water is supplied to the nozzle from an external source through a supply hose l9 and is controlled by a valve 20. The water nozzle is preferably adapted to produce a divergent or expanding stream of water. The water nozzle is mounted so that its tip is close to the tip of the cutting torch whereby the expanding or divergent water stream can enter the kerf close behind the oxygen cutting jet.

The torch carriage l2 and the work-piece W are properly positioned relative to each other and then the metal of the work-piece, where the cut is to be started, is preheated to kindling temperature by the heating flames of the cutting torch unless this preheating can be dispensed with in case the entire work-piece is sufiiciently hot when cut. The jet of cutting-oxygen represented at 2| is then turned on and the torch carriage started. The water supply is then turned on to produce the water stream represented at 22. As the carriage I2 progresses, the oxygen jet 2! cuts a kerf 23 in the work-piece W by the thermochemical action of the oxygen jet on the ferrous metal of the work-piece. The cutting action produces molten metal and molten oxides which are largely blown out of the kerf by the force of the oxygen cutting jet, but some of it runs down under the bottom edges of the kerf and clings to the workpiece. The water stream 22 is so directed and has such an angle of divergence that it strikes the side walls of the kerf (Fig. 3) near the bottom of the kerf immediately following the oxygen cutting jet 2 I r (Fig. 2). The Water stream preferably does not lag behind the oxygen cutting jet at the bottom of the kerf by more than of an inch and, of course, must not chill the metal to be cut by being directed against the uncut section of the work-piece. The original setting of the water stream must take into account the cutting speed to allow for drag, especially on thick I and forms steam pockets in it and accelerates its at kindling temperature, and producing steam pockets in the molten material that is not blown away from the kerf and that clings to the work along the bottom edges of the kerf by projecting a streamof water downwardly into the kerf so that all parts of the water stream contact with the work-piece below the upper surface thereof and contact with the molten material only after the molten material has substantially reached the bottom edges of the kerf and while it is still cling-- ing to the work and before it has solidified,

whereb; the heads into which such molten material solidifies are porous and can later be readily 4 removed from the work, the stream of water being projected into the kerf angularly with respect to both the work-piece and the cuttingoxy gen jet.

2. In the method of thermochemically cutting through ferrous metal work-pieces by directing a jet of cutting-oxygen downwardly toward the work-piece and advancing it across the workpiece while the metal is at kindling temperature, the improvement which comprises projecting a stream of water downwardly and angularly into the kerf from that side of the work-piece at which the cutting-oxygen jet is projected against it and closely behind the cutting-oxygen jet and so that it intersects the line of the cutting-oxygen jet at a region at least as low as the bottom of the kerf and so that the water contacts with the moltenmaterial that clings to the work at the bottom edges of the kerf only after the molten material has substantially reached the bottom of the kerf to form steam pockets in such molten material whereby the beads into which such molten material solidifies are porous and can later be readily removed from the work.

WILLIAM T. DAVIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Great Britain Sept. 23, 19:46 

1. THE METHOD OF THERMOCHEMICALLY CUTTING THROUGH FERROUS METAL WORK-PIECES AND PREVENTING BEADS OF SOLIDIFIED MOLTEN MATERIAL FROM BECOMING SO WELDED TO THE WORK ALONG THE BOTTOM EDGES OF THE KERF THAT IT IS DIFFICULT TO REMOVE, WHICH COMPRISES DIRECTING A JET OF CUTTING-OXYGEN DOWNWARDLY TOWARD THE WORK-PIECES AND ADVANCING IT ACROSS THE WORK-PIECE WHILE THE METAL IS AT KINDLING TEMPERATURE, AND PRODUCING STEAM POCKETS IN THE MOLTEN MATERIAL THAT IS NOT BLOWN AWAY FROM THE KERF AND THAT CLINGS TO THE WORK ALONG THE BOTTOM EDGES OF THE KERF BY PROJECTING A STREAM OF WATER DOWNWARDLY INTO THE KERF SO THAT ALL PARTS OF THE WATER STREAM CONTACT WITH THE WORK-PIECE BELOW THE UPPER SURFACE THEREOF AND CONTACT WITH THE MOLTEN MATERIAL ONLY AFTER THE MOLTEN MATERIAL HAS SUBSTANTIALLY REACHED THE BOTTOM EDGES OF THE KERF WHILE IT IS STILL CLINGING TO THE WORK AND BEFORE IT HAS SOLIDIFIED, WHEREBY THE BEADS INTO WHICH SUCH MOLTEN MATERIAL SOLIDIFIES ARE POROUS AND CAN LATER BY READILY REMOVED FROM THE WORK, THE STREAM OF WATER BEING PROJECTED INTO THE KERF ANGULARLY WITH RESPECT TO BOTH THE WORK-PIECE AND THE CUTTINGOXYGEN JET. 